I believe this has been resolved and nowadays you can write it like this:
import com.fasterxml.jackson.annotation.JsonSubTypes
import com.fasterxml.jackson.annotation.JsonTypeInfo
@JsonTypeInfo(
use = JsonTypeInfo.Id.NAME,
include = JsonTypeInfo.As.PROPERTY,
property = "type")
@JsonSubTypes(
JsonSubTypes.Type(value = Comment::class, name = "CommentNote"),
JsonSubTypes.Type(value = Photo::class, name = "PhotoNote"),
JsonSubTypes.Type(value = Document::class, name = "DocumentNote"))
interface Note
Note the missing @ and class notation in the JsonSubTypes.Type.